Sound reproducing system



SOUND REPRODUC ING SYSTEM Filed Feb. 10, 1932 I INVENTOR E. GOSMANN q.AJhdi.

A T TORNEV Patented Oct. 11, 1932 UNE STATES PATENT oFFIcE f ENARTGOSMANN, OF ELMWOOD PARK, ILLIROIS, ASSIGNOR TO WESTERN ELECTRIC vCOMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORKSOUND REIBRODUCING SYSTEM Application filed February 10, 1932. SerialNo. 592,063.

This invention relates to communication systems and particularly tothose systems in which a plurality of originating channels may beconnected to a common terminating channel.

' The object of the invention is the provision of means for graduallyreducing the power transmitted to the terminating channel from oneoriginating channel and gradually in creasing the power transmitted tothe terminating channel by another originating channel.

A feature of the invention is the provision of switching means which donot involve any sliding contacts in the communication channels.

Another feature of the invention resides in the use of a plurality ofthermionic devices for switching the originating channels to theterminating channel.

A further feature of the invention resides in the use of switchingdevices in which, after the change has been initiated by the attendant,the time of the change is automatically controlled by the switchingdevice.

For convenience of description, the inven tion has been shown embodiedin a sound reproducing system but it will be obvious that the inventionmay be applied to many other communication systems.

In known sound reproducing systems, in many cases, a plurality ofso-undrec'ords must be reproduced in succession by the same reproducingchannel, without producing a noticeable break between the successiverecords. For example, the known feature presentations generally comprisefrom five to ten reels of pictures with their corresponding records. Atthe end of each reel the picture must fade out and the beginning of theneXt reel must fade in so that the change-over is not perceptible. Thesound records may be of any known type such as a photographic record,disc record, magnetic record or other types and are translated intosound modulated electric currents by suitable translating devices. Thepower delivered to the reproducing channel by the translating devicecorresponding to the first reel, which may be termed the outgoingtranslator, must decrease at the change-over, While the power deliveredto the reproducing channel by the translating device corresponding tothe sec ond reel, which may be termed the incoming translator, mustcorrespondingly increase at the change-over.

In accordance with the present invention the output of the outgoingtranslator is supplied to a thermionic device which supplies anamplified output to the reproducing channel. Similarly, the output ofthe incoming translator is supplied to a second thermionic device. alsoconnected to the reproducing channel. At the change-over theprojectionist operates a switch which opens the cath. ode circuit of thefirst thermionic device and closes the cathode circuit of the secondthermionic device. The cathode of the first device cools at a rate.determined by its design, the electron emission decreases, and the powerdelivered to-the reproducing channel decreases to zero. Conversely, thecathode of the second device heats up, the electron emis sion increases,and the power delivered to the reproducing channel increases to normal.

If the cathode circuit of the second device is closed by the sameoperation which opened the cathode circuit of the first device, the twodevices will operate simultaneously decreasing the output from theoutgoing trans: lator while the output from the incoming translator isincreasing. The time taken to make the change-over will then bedetermined by the design of the cathode circuits only and may becorrelated to the length of the fade-out and fade-in on the picturereel.

By permitting a short time to elapse between the opening of the firstcathode circuit and the closing of the second cathode circuit, theoutput from the outgoing translator may be permitted to fall to a smallvalue before the output of the incoming translator is sup plied to thereproducing channel.

The drawing discloses in schematic form an embodiment of the invention.

Modulated currents from a translating device .1 are amplified inanamplifier 2 and applied through atransformer 3 to the in put of athermionic amplifier 4. The amplified currents in the output of theamplifier 4 are supplied to a transformer 5, and may be amplified in asuitable amplifier 6. The amplified output of the amplifier 6 may beutilized in any desired manner, for example, as shown, the amplifiedoutput may actuate a reproducing device 7.

The communication channel formed by the translating device 1, amplifier2, transformer 3 and amplifier 4 may conveniently be termed anoriginating channel. Similarly, the communication channel formed by thetransformer 5, amplifier 6, and reproducing device 7 may be termed aterminating channel.

Current is supplied from battery 8 through the primary winding oftransformer 5'to the anode of the amplifier 4, thence through amplifier4 to its cathode and through the ground to battery 8. Current is alsosupplied from battery 9 through resistor 10, springs 11 and 12, cathodeof amplifier 4, through the ground to battery 9. The currents frombatteries 8 and 9 energize the amplifier 4.

A key 13 may be located at any point convenient to the operator. Whenkey 13 is closed, current flows from battery 14, through key 13 and thewinding'of a relay 15. .Relay 15 is energized and closes a circuitbetween springs 11 and 16, and then opens the circuit between springs 11and 12. When the circuit is opened between springs 11 and 12 currentceases to fiow in the cathode of the amplifier, 4 and the modulatedpower from the translating device 1 supplied to the reproducer 7decreases and finally becomes negligibly small. lNhen the circuit isclosed between springs 11 and 16, current can flow from battery 9,through resistor 10, springs 11 and 16, cathode of a thermionicamplifier 17, through ground to battery 9. Modulated currents from atranslating device 18 are amplified by an amplifier 19 and appliedthrough a transformer 20 to the amplifier 17. When current is applied tothe cathode of the amplifier 17, the amplified output of'the amplifier17 will gradually increase to normal. The output of the amplifier 17 issupplied through transformer 5, and amplifier 6 to the reproducingdevice 7. Current from modulated power transmitted from the translatingdevice 18 to the reproducing device 7 will gradually increase. Theterminating channel has thus been switched from one originating channelto another. The relay 15 may be replaced by any suitable key and may bearranged so that the modulated power transmitted by the amplifier 4falls to a small value before the cathode circuit of the amplifier 17 isenergized.

' The translating devices 1 and 18 are shown reproducing a disc soundrecord rotated by a conventional turntable. Obviously, these translatingdevices may take a variety of forms suitable for translating other typesof sound records, such as photographic, magneticor chemical records, ormay be conventional microphones which translate acoustic waves intomodulated electric waves.

What is claimed is:. 1

1. In combination, a plurality of originating communication channelsindividually connected to the inputs of a plurality of thermionicdevices, said devices each having an anode, a cathode and a controlelectrode, a terminating communication channel connected to the outputsof all of said thermionic devices, and switching means for energizingthe cathode of one of said thermionic devices 7 and, at will,deenergizing the cathode of said thermionic device and energizing thecathode of another of said'thermionic devices.

2. In combination, a plurality of devices for translating individual.sound records into modulated electric waves, aplurality of thermionicdevices individually controlled by said modulated waves, said deviceseach having an output circuit, an input circuit and a cathode, soundreproducing means connected to the outputs of all of said thermionicdevices and switching means for energizing the cathode of one of saidthermionic devices and, at will, deenergizing the cathode of saidthermionic device and energizing the cathode of another of saidthermionic devices.

In witness whereof, I hereunto subscribe my name, this 1st day ofFeb.1932. .ENART GOSMANN.

battery 8 is supplied through the primary winding of transformer 5 tothe anode of the amplifier 17 and flows through the amplifier 17 toground and thence to battery 8, energizing the output circuit of theamplifier 17.

The cathode of the amplifier 4 will take an appreciable time to cool andsimilarly, the cathode of the amplifier 17 will take an appreciable timeto heat up to normal. During the time in which the cathode of theamplifier 4 is cooling, the modulated power transmitted from thetranslating device 1 to the reproducing device 7 will graduallydecrease.

' Similarly, during the time in which the cathode of the amplifier 17 isheating, the 1

